diff --unified --recursive --text olive-0.1.2-orig/project/proxygenerator.cpp olive-0.1.2-new/project/proxygenerator.cpp
--- olive-0.1.2-orig/project/proxygenerator.cpp	2019-11-11 03:05:02.000000000 -0300
+++ olive-0.1.2-new/project/proxygenerator.cpp	2020-06-23 21:07:29.808353198 -0300
@@ -167,7 +167,13 @@
   }
 
   // write video header
-  avformat_write_header(output_fmt_ctx, nullptr);
+  int error_code;
+  error_code = avformat_write_header(output_fmt_ctx, nullptr);
+  if (error_code < 0) {
+    qWarning() << "Failed to write video header";
+    cancelled = true;
+    skip = true;
+  }
 
   // packet that av_read_frame will dump file packets into
   AVPacket packet;
